#screen {
	width:600px;
	height:400px;
}

div.gridodd{
	width:20px;
	height:20px;
	float:left;
	cursor:pointer;
	background-color: rgb(128, 128, 128);
}

div.grideven{
	width:20px;
	height:20px;
	float:left;
	cursor:pointer;
	background-color: rgb(192, 192, 192);
}

#history span {
	float :left;
}